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Syntax

Lisp syntax is very simple: there are few rules to remember.

Syntax is made up of S-expressions. An S-expression is either an atom or a
list.

Atoms can be numbers like 10, 3.14, or symbols like t (the truth
constant), +, my-variable. There’s also a special kind of symbol called
keywords, which are colon-prefixed symbols like :thing or :keyword. Keywords
evaluate to themselves: you can think of them sort of like enums.

Hello, World!

Without further ado:

CL-USER> (format t "Hello, world!")
Hello, world!
NIL

Comments

;; Single line comments start with a semicolon, and can start at any point in the line
#|
This is a multi-line comment.
#|
They can be nested!
|#
|#